Laboratory Study
Eye (2007) 21, 395–401. doi:10.1038/sj.eye.6702239; published online 27 January 2006
Rage gene promoter polymorphisms and diabetic retinopathy in a clinic-based population from South India
S Ramprasad1, V Radha1, R A Mathias2, P P Majumder3, M R S Rao4 and M Rema1
- 1Madras Diabetes Research Foundation & Dr Mohan's Diabetes Specialities Centre Gopalapuram, Chennai, India
- 2Genometrics Section, Inherited Disease Research Branch, National Human Genome Research Institute, National Institutes of Health, Baltimore, MD, USA
- 3Indian Statistical Institute, Kolkata, India
- 4Department of Biochemistry, Indian Institute of Science, Bangalore, India
Correspondence: M. Rema, Madras Diabetes Research Foundation, 4, Conran Smith Road, Gopalapuram, Chennai, 600 086, India. Tel: +91 44 2835 9050; Fax: +91 44 2835 0935. E-mail: drrema@vsnl.com
Received 27 May 2005; Revised 27 October 2005; Accepted 28 November 2005; Published online 27 January 2006.
Abstract
Purpose
The main objective of this study was to evaluate if the -429T/C, -374T/A and 63 bp deletion polymorphisms in the RAGE gene are associated with diabetic retinopathy (DR) among Type 2 diabetic subjects in a clinic-based population from South India.
Methods
We screened 149 normal glucose tolerant subjects (NGT), 189 Type 2 diabetes subjects without retinopathy (DM) and 190 subjects with DR for these polymorphisms using the PCR-RFLP method. DR was diagnosed by grading color fundus photography. Logistic regression models were used to evaluate the association of individual polymorphisms with DR. Expectation–maximization algorithms were implemented in haplotype tests of association to examine the combined effects of -429T/C and -374T/A polymorphisms on DR.
Results
The allelic frequencies of -429T are 0.83 in NGT, 0.84 in DM and 0.85 in DR subjects, and that of -374T are 0.93 in NGT, 0.92 in DM and 0.88 in DR subjects. The -374 polymorphism was found to be associated with non-proliferative retinopathy when this subgroup was compared to the DM group (OR=1.814, 95% CI=1.005–3.273). However, this association was not obvious when both the subphenotypes of DR (the nonproliferative and proliferative DR groups) were studied jointly. We found no evidence for associations between the -429T/C polymorphism and the DR phenotype. Finally, extension to a 2-SNP haplotype did not reveal any significant statistical difference between the groups (P=0.668).
Conclusion
In this study, we found a modest association with the -374T/A polymorphism in the nonproliferative DR subgroup.
Keywords:
diabetic retinopathy, RAGE polymorphism, -374 TA, -429 TC, 63 bp deletion
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